Some people consume chronically glutamine (GLN) in high quantities (~40 g/d), although a number of biochemical pathways and cellular functions may be negatively affected. The following side effects of GLN supplementation are discussed: (1) Alterations in amino acid transport-as GLN shares the transporters with other amino acids, enhanced GLN intake may impair amino acid distribution among tissues and their absorption in the gut and kidneys. (2) Alterations in GLN metabolism-GLN supplementation may impair synthesis of endogenous GLN and enhance glutamate and ammonia production. (3) Alterations in ammonia transport-GLN supplementation may impair ammonia detoxification and negatively affect the role of GLN as the carrier of ammonia among tissues. (4) Abnormalities in aminoacidemia-increased plasma levels of GLN, glutamate, citrulline, ornithine, arginine, and histidine and decreased levels of valine, leucine, isoleucine, glycine, threonine, serine, and proline are reported. (5) Alterations in immune system-as GLN has immunomodulating properties, the effect of chronic GLN consumption on the immune system needs to be assessed. (6) Effect on tumor growth-it should be elucidated whether chronic intake of GLN increases the risk of cancer. (7) Effect of the withdrawal of GLN supplementation-due to the adaptive response of the organism to enhanced GLN consumption, the withdrawal of GLN may enhance the risk of health problems resulting from GLN deficiency. It is concluded that enhanced intake of GLN has substantial side effects, and long-term studies should be performed to justify chronic consumption of a GLN-enriched diet.

I remember years ago, our own Necrosis (yousmokepole) mentioned the concept of certain amino acids competing with the transport of others, and thus should not be taken together. I don't recall any further elaboration, but #1 above explains it.

This is the first I've heard of glutamine's other sides; some of them pretty serious, too. As an OTC supplement, I doubt this will receive the proper research it deserves to determine its longterm safety - at least not anytime soon.

I briefly used glutamine years ago, noticed nothing, and discontinued.

Glutamine + vit c helps me heal faster/not get sick. It also seems to mildly help with recovery that's about it... And I did in fact come upon medical journals which illustrate its benefit in healing, preventing infections, speeding healing/infections/etc... as it is one of the main ingredients in the building up of the immune system

I remember years ago, our own Necrosis (yousmokepole) mentioned the concept of certain amino acids competing with the transport of others, and thus should not be taken together. I don't recall any further elaboration, but #1 above explains it.

This is the first I've heard of glutamine's other sides; some of them pretty serious, too. As an OTC supplement, I doubt this will receive the proper research it deserves to determine its longterm safety - at least not anytime soon.

I briefly used glutamine years ago, noticed nothing, and discontinued.

Great abstract!

Isn't this the same reason it's always been said it's a waste to mix your BCAA's with your protein shake?

In terms of sports nutrition, the branched chain amino's serve to stimulate global rates of protein synthesis in skeletal muscle. Since that is the case, then it makes sense to ingest them in the presence of other complete proteins. By themselves, they seem much less effective.